Manufacture of thioacetic acid and diacetyl sulfide



May 19, 1953` w, W CROUCH l 2,639,293

MANUFACTURE OF THIOACETIC ACID AND DIACETYLSULFIDE 4 Filed Dec. 16, 1948 DIACETYL SULFIDE A T TORNEVS Patented May 19, 1953 MANUFACTUBE F THIOACETIC AGH)y DlACETYL SULFIDE WillieW. Crouch, Bartlesville, Okla., assigner to Phillips. Petroleum Company, a `corporationof Delaware app-inane .December 1c, laisserai No. ,65.6.22

(Cl. Z60m-500) 13 Claims.

This invention relatesv to thioacetic acid and diacetyl sulfide. relates to the preparation of thioacetic acid and diacetyl sulfide.

Thicacetic acid and diacetyl sulde, have been prepared by various procedures. vreported. in the art, all of which are `either expensive or ineicient, or both, as regards their .commercialiscale application. One recently proposed-method for the preparation of thioacetic acid involves the reaction of acetic acid anhydride with .hydrogen sulde., wherein only one .of the 'two acetyl groups of the anhydride can be converted tothioacetic acid for each mole oi" the acid anhydride 4that reacts. One reported method for preparing vdiacetyl sulfide involves the lreaction o f 4acetyl chloride with a suliide of an .alkali metal, in which case the cost of the acetyl chloride, .as 1a kstarting material, in the commercial vscale production of low cost diacetyl sulfide, .is prohibitive.

rlhis invention is concerned With-the ultizatiori of lrelatively inexpensive raw materials to produce thioacetic acid and diacetylsulflde, each in high yield and purity.

.en object of this; invention is tovprovide aprecess for the production .of 'thioacetic acidl and diacetyl sulfide.

Another object is to vprovide aprocess .for the interaction .of ketene vwith hydrogen sulfide to produce both thicacetic acid and diacetyl sulfide.

Another Objectis to `pi'ovidciior the -production of thioacetic acid and diacetyl suldeiromketene anclhydrogen sulfide..

Other .objects will'be apparent, to thoseski-lled in the art, iromtheaccmpanying discussion and disclosure.

i' have now discovered .a new .and efiicient cata-lytic process ,for .tico .production .of 'thioacotlo anciana Ydiaeetyi.su1:i, ie.. Wheroi .both .ci these compcundsare producedover ad ran'gec'f process conditions. Inaccordane with iny invention .ketene Kand hyldrggcn `sulride .are introduced in a molo ratio vof hydrqgelfi sulfide to ketone Within -thel'allgeof 0.211 to "8.;1, into con.- tact withasolid adsorbent contact catalyst tained at .a temperature yvithinlflioraig, to 4000211, .andreactedjin voporrbase. some .conditionslooth thoacetoaod all@ loolyl sulfide.are.iormedinsubstantial amoiintabutas will. bemore `fully disclosed .hercnllhaye further found that .conditions maybe sc `clfiiosen that either oneor .the .other may .be produced ,as ,a major product.

.A particularlyimporiant feature of my mycoii'onis ...the vuse y.of a .solid ,adsorbent .contact catalyst. Attempts toeifcct yaporgphascroa tion of ketone With hydrogen sulfide underconditicns similar .to .those 'of therrocess of ...invention in one aspect this invention but with .no catalyst bein-g employed, have resultedin no detectable amounts of thioacetic acid or diacetyl sulfide being formed Many ,solid adsorbent contact catalysts may be used as catalysts in the process of my invention. Among the `solid adsorbent Contact catalysts which I prefer to use, are included synthetic nor natural occurring aluminas, catalysts containing zirconiav alumina such Yas titania-alumina, alumina, chroinia-aluinina, rnolybdena-alumina,

vanadium pentoxidev-a-lumina, cupric oxiole-ali i'l mina, thoria-alurnina and the like, nsuliide catalysts such as molybdenum sulfide, and simple solid adsorbent contact catalysts 'such as activated charcoal. However, no ooo of those .CotalyStS is the equivalent of oily other. osoooioily insofar as conditions oi optimum liso. 'catalyst' life, yield per pass of desired product, and ,thc like. arc concerned.

Although temperatures within .tho rango of .5.0- to 400 F. may bcomployeo in ihopiooiioo of my.

invention., ,the preferred .range is usually Within the 'limits of Yfrom 1,50 to `350" F. Contact time may .generally loo chosen .Within .tho .limits of 0.5 to 1D secondo; although contact .timos outside .that

broad .rango mayloootilizod. .Moro often., o con-- tact timowiihin .the rango .of 1 to 5 Seconds advantageously. employed. Usually, a Contact time extended Ice yoiid'thobroad .range of 0.5 to

when .introducing ,.liydiooon .Suldo and ketone.

reactants .in contact with .tho Vcatalyst in o. molo ratio of hydrogenv sulfide to ,ketone Within the broad .rangeof .Q ,Zzlto 1, already discussed, I have found thotootimum -yioldoof thioocoic acid are .obtained when introducing .hydrogen `S11-lodo andkotcnc Vcontact y/.iththo-.oatalyoi ,in o molo laGOfQf .hydrfgiirl .Sillld f ketone Within lh? limits -of .2.21.5@0 521,A diacotyis fide od hooihoimolo-rotio s-Withiii......e longo.. ...1.

The Elretenc-i..used :inathe vpracticeof .my invenu tion may :be relatively Apu-i,"e,.ci' maybe associated Withothervmaterials. Ketene-containirigstreams comprising trom x10 :to .100 per cent by .weight ketene `may be yemployed. Ketene -obtaiiiediirom the pyrolysis of -di-ketene may be used, or liiripui'e streams obio'incd'by @my ci various 'iiooyvo' .oyroiysis methods Winayibc .satisfactorily loyi Keime-.containing oiucotsirooi the oyrolyoisof d .that optimum yields oiacetone, the pyrolysis or dehydrogenation of acetaldehyde, the pyrolysis of acetic acid and the pyrolysis of dehydration of acetic anhydride may be employed. Of the various sources of ketene above mentioned, the pyrolysis of acetone has proven to be particularly satisfactory, not only from the standpoint of the ease and eflciency with which acetone may be converted to ketene, but also in view of the low cost of acetone as a raw material.

Ketene is manufactured commercially by the pyrolysis of acetone, perhaps more often than by any other method. This process has been studied extensively by workers in the art, and many references are available `as to' the effect f reaction variables such as temperature, pressure, residence time, catalysts and materials of construction of the pyrolysis tube. Generally, yields in the range of about 40 to 80 percent or higher are obtained when acetone is pyrolyzed at temperatures around l300 F. The most important variable controlling the ultimate yield of ketene is the conversion of acetone per pass; lower per pass conversions give higher ultimate yields. Thus, in selecting the pyrolysis temperature and rate of charge of acetone to a given pyrolysis tube, a compromise is required between, 1) operating to obtain a high ultimate yield of ketene from the acetone consumed, by using relatively low temperatures and short residence times to obtain low conversions per pass, or (2) operating for maximum ketene production from a given pyrolysis apparatus by using higher temperatures and longer residence times to obtain higher conversions per pass at the sacrifice of ultimate yield.

In a preferred embodiment of my invention, ketene is prepared by the pyrolysis of acetone, and the resulting ketene-containing pyrolysis product is passed together with hydrogen sulfide, through a bed of solid adsorbent contact catalyst under conditions suitable for production of thioacetic acid and diacetyl sulfide. Although both the thioacetic acid and the diacetyl sulfide are formed in all instances, reaction conditions, particularly the mole ratio of reactants introduced into contact with the catalyst, may be selected for obtaining one product in optimum yield at the expense of decreased yield 0f the other.

In order to present my invention more clearly reference is made to the attached drawing which diagrammatically illustrates a preferred embodiment of my invention. It is to be understood that the flow diagram is diagrammatic only and that it may be altered in manyrespects by those skilled in the art and yet remain within the intended scope of my invention.

y Referring to the drawing, acetone from line I0 is introduced through line I2 to pyrolysis zone I3, alone or together with recycled acetone from line II, discussed hereafter. Pyrolysis zone I3 is maintained usually at atmospheric pressure, and at a temperature in the range of 700 to 1400n F., under-which conditions acetone therein is pyrolyzed to form ketene as a chief pyrolysis product. Other pyrolysis products formed in zone I3 are chieiy, carbon monoxide, carbon dioxide, and methane together with lower yields of heavier by-product materials, including some ketene polymer. Total effluent from pyrolysis zone I3 is passed through line I4 to fractionation zone I6 wherein it is separated into light ketenecontaining overhead product, and residual product, comprising unreacted acetone and normally liquid pyrolysis by-product. Ketene-containing overhead product separated in zone I6 contains from l0 to as high as 80 to 90 per cent ketene, depending upon the selected pyrolysis conditions. Residual product from fractionation zone I6 is passed through line I1 to acetone purification zone I3 wherein it is separated into normally liquid pyrolysis by-product, and unreac'ted aceproduct .separated tone of desired purity for recycling. Pyrolysis in zone I8 is withdrawn through line I9. Acetone from zone I8 is recycled through lines 2I, II and I2 to pyrolysis zone I3, orit may be Withdrawn from line 2l through line 22, for further utilization, not shown. Overhead product from fractionation zone I6 comprises ketene together with other light pyrolysis product, predominantly methane, carbon monoxide and carbon dioxide. Ketenecontaining product from zone I6 is passed throughline 23 and admixed in line 24 with hydrogen sulfide introduced through line 29. Any unreacted hydrogen sulfide and/or any unreacted ketene, recovered from the reaction product, may be recycled to line 24, as described hereafter. The resulting ketene-hydrogen sulde mixture in line 24 is passed into catalyst chamber 32, and contains hydrogen sulfide and ketene in a respective mole ratio within the limits of 0.221 to 8:1, dependent upon the relative yields of thioacetic acid and diacetyl sulfide sought; the proper mole `ratios for obtaining optimum yields of each product are discussed elsewhere in this specification. Catalyst zone 32 contains a solid adsorbent contact catalyst maintained at a temperature within the range of 50 to 400 F. The selected catalyst may be, any one of the types already discussed, lfor example, granular alumina. Contact time in catalyst zone 32 is usually within the range of from 0.5 to l0 seconds, although shorter or longer times may be utilized. In most cases ketene is substantially completely reacted, although when introducing hydrogen sulfide in a relatively low mole ratio to ketene, as when predominantly forming diacetyl suliide, some ketene may be incompletely reacted, depending upon the specific temperature and time conditions selected. Total eiiuentffrom catalyst zone 32 is passed through line 33 to condenser 34 wherein normally liquid product is condensed. Total eiiluent from zone 34, containing'both condensate and uncondensed gas is passed through line 33 to accumulator 3'1 wherein a liquid condensate layer is separated from the. uncondensed gas. Uncondensed gas from zone'3'I contains predominantly unreacted hydrogen sulfide, any unreacted ketene, carbon monoxide, carbon dioxide and methane, and is passed through line'38 to'gas purification zone 39 comprising fractionation equipment,'ab sorption equipment and other 'facilities well known to those skilled in the art, adaptable to the recoveryof hydrogen suliide and any unreacted ketene from the material introduced through line 38, not individually illustrated. Any unreacted-ketene separated in zone 39 may be recycled through lines 29, 2 8 and 24 to catalyst zone 32. However, if desired, unreacted ketene from zone 39 present inline 29 may be withdrawn through line 39 for' utilization elsewhere, not shown.' Hydrogen sulfide separated in zone 39 may be recycled through lines 21 and 24 to reaction zone 32, or may be withdrawn from line 21 through line 35 for utilization elsewhere, not shown. Gas residue predominantly methane, carbon monoxide and carbon dioxide, is passed from zone 39 through line 25 for further utilization, notshown..A i

Liquid product fromzone 31 contains thioaeoaccsi acetic @Cid and diacetyl sulfide, and passedthroughline 41 to product separation means 42 comprising fractionationequipment, separators, storage facil-ities and the like,- no-t 4indiSIid-ua'lly illustrated, suitablev'for use `recovery of thethioacetic acid and diacetylsulde product. From zone `42 is withdrawn thioacetic acid through fline 44 and diacetyl -sulde'through line y113 fas produc-ts of the lprocess. -Ieavs7 producticomprising some 'lgetene polymer,- 4high molecular Weight sulfur-containing -`materials,-'and thai-ilse, is withdrawn from zone 42 through: linefAS.- Ketenefrom any source other than acetone pyrolysis, may be introduced `to catalyst chamber 32 through lines -40 xand 24."-

Diacetyl sulfide undergoes r-apid'decomposition at-*its `boiling point 'at atmospheric pressure'.` although vtlnoaeetic4 acid 4can be fraction-ated- ,Example I Vibry acetonewas ,fed continuously fto a nyrclysis furnace .at the rate of 3.26 moles per hour. The furnace temperature was maintained at 13.3.09 F. The .eiiuen't lfrom the fnrnace Ywas passed contnucnsly, to aa lfracti.o nefuion column. The im changed :acetone was ,removed from the iractionator as bottoms. Analysis showed :that the easeousfoverhead from the ractionator contained 0,938 mole 111er v'hour of ketone comprising-.about :i6-might ner cent .of ythe stream. This stream 'nos continuously mixed wit-ln .1:83 moles per hour of dry, gaseous hydrogen s Inde, corre- Spending .to e hydrogen snlnde to 4,ketone mole ratio of @1.961. llhis vco...fnbined stream was passed through .av-.250cccatalyst chamber 'filled with zoneeeighth inch alumina pellets. y.t..f.e.nfi peinture was :maintained at 1F. Total A,ef-

-uent `fremithe reactorv Lowas .vapor '1 phase and was -continuousliv cooled `to"corldorlse' the desired' producm-leredeminantly thioaceticV acid.l una-1 condensed gases `were* collected .for 4the recovery acetic acid product was then purified fbydistillation. In this yWay o 0.422 mole `iper"Jnonr of thine acetic acid concentrata-boiling at to 197 F.,

`Was obtained, representing a yield of 91 per cent of theory. The identityofthethioacetic acid was established by (1') its `reaction l'with aniline at room temperature to-form acetanildel'andv (2) its yo,xica-tionwith cupric chloridesolutiontoproe ducef-diacetyi disulflde.- 'Relativelylo-W yields of diacetyl sulfide were 1 obtained;-

A sei-ies of runs was carried butin exactlr'the same manner and in the same equipment'as-in Example I except that the `Catalyst was bauxite pebbles and the temperature was varied as show in theftable below. o

Telnpeingme, @'F.

Eample HP1 Mol Ratio Eyewear.; .Smilde 1 lieten@ .C Per Bound y0f Ketcne" Example IV A seriesfof. runs wasx'madeiunder thetsame conditions'and `in the same equipmentv as in Ex ample I e-xcept thatmillier/catalysts were .eine ployedas shown inthe followingtable Y Catalyst Yield of Thicacetic l Catalyst Preparation. Acid, @dftem wenn oQ-meet- Pel-enf i'iiy 51umjna -80 titanio 20 powders of the two 0x' es mixed tgs4 g gather endpiliefi; ,.celcin Do g4 ;;iiogium,n itrate---, ,1,6 v@ilumine pills dip-Doethorium 83 niti'ate'soiution and dri p0-. se zirconia.... V 20 goed :0f the q des :nix 80 together .and nilicd, eelcined.- 330 (il) alumina pills` dippedin ammonium "77 tungstate and dried, 110.1; salaried.. Do 82 @nonna 1,8 alumina pills diopedin cnromio cold 77 so1ution, dried'and calcined. no ce cupnc oxlde .f :10y alu d llm.- impregnated with cuori@ 75 93.1. e.- Do V91 molybdena 9 alumina 4pills dipped ammonium 64 moiybcote, dried and oolcilrlei;` iDo.... .90 .vanodulm pentoxide 10 @lemma pills .dip er1 in ammonium 63 metavenadatef ed d-ca'leine'd.` .bainitepebbles-. --1-.,-.1T 59 nocatalyst .-.,f 0

. @This catalyst-is:lvxpercentftlmgsten expressed as tungstentrioxide..

The pilled catalysts were all one-eighth inch with the exception of the alumina-titania catalyst which Was seven thirty-seconds inch. It will be noted that no detectable amount of thioacetic acid was formed when no catalyst was employed.

Diacetyl sulfide was attained in yields considerably lower than those of thioacetic acid.

Example V TWO runs were made using activated charcoal as the catalyst but otherwise carried out in the same manner as in Example I and in the same equipment except that the temperature in the catalyst chamber was maintained at 122 F. in one run and at 212 F. kinthe other run. A yield of 37.2 per cent of theory, of thioacetic acid, based on ketene was obtained at 122 F. While a yield of only- 17.6 per cent o f theory was obtained at 212 F.

' Example VI Ketene prepared from dry acetone -in accordance with the procedure of Example I was admixed with hydrogen suliide and continuously passed through a reaction zone containing 200 cc. of pelleted bauxite catalyst maintained at a temperature of 172 F. Ketene was fed at a rate of 0.71 mole per hour and the hydrogen suliide feed rate was 0.35 mole per hour. After 7.5 hours of operation, the reaction was terminated, providing a total yield of 189 grams of crude product. In the fractionation of the crude product, 107 grams of a diacetyl sulfide-rich fraction boiling in the range of 122-134 F. under a pressure of approximately mm. was obtained. 74 grams of an overhead fraction boiling below 104 F. at 20 mm. and comprising principally thioacetic acid, Was obtained.

I am not certain as to the mechanism by which the reaction of ketene With hydrogen sulfide takes place in the process of my invention. However, itis apparent that when employing relatively low mole ratios of hydrogen sulde to ketene, discussed hereinabove, a major proportion of the hydrogen sulfide reactswith an equimolar proportion of ketene to form thioacetic acid, and the thioacetic acid thus formed, then reacts with ketene, present in excess, to form diacetyl suliide.

As Will be evident to those skilled in the art, various modifications of this invention can be made, or followed, in the light of the foregoing disclosure and discussion, without departing from the spirit or 'scope of the disclosure or from the scope of the claims.

I claim:

1. A process for the production of thioacetic acid and diacetyl sulde, comprising passing hydrogen sulfide and ketene in a mole ratio of hydrogen sulfide to ketene within the limits of 0.2:1 to 8:1 into contact with an alumina-containing catalyst maintained at a temperature within the limits of 50 to 400 F. and in the presence of said catalyst reacting hydrogen sulde with"V presence of said catalyst reacting` hydrogensulg iide with ketene each in vapor phase, and recovering thioacetic acid and diacetyl sulfide fromI the resulting reaction product.

3. A process for the production of thioacetic acid and diacetyl sulde comprising reacting hydrogen sulde and ketene each in vapor phase in the presence of a solid adsorbent contact catalyst at a temperature Within the range of 50400 F. with a mole ratio of hydrogen suliide to ketene within the limits of 0.2:1 to 8:1, and recovering thioacetic acid and diacetyl sulfide from the resulting reaction product.

4. A process for the production of thioacetic acid, comprising introducing hydrogen sulfide and ketene in a mole ratio of hydrogen sulde to ketene within the limits of 2:1 to 5:1 to a reaction zone containing an alumina catalyst and therein reacting hydrogen sulfide with ketene each in the vapor phase at a temperature Within the limits of to 350 F., recovering thioacetic acid as a product of the process.

5. A process for the production of diacetyl sulde, comprising introducing hydrogen sulde and ketene in a mole ratio of hydrogen sulfide to ketene Within the limits of 0.2:1 to 2:1 to a reac.

tion zone containing an alumina catalyst and therein reacting hydrogen sulde With ketene each in the vapor phase at a temperature Within the limits of 150 to 350 F., and recovering diacetyl sulfide as a product of the process.

6. A process for the production of thioacetic acid comprising introducing hydrogen sulfide and ketene in a mole ratio of hydrogen sulfide toA ketene within the limits of 2:1 to 5:1 to a reaction zone containing activated charcoal as a catalyst and therein reacting hydrogen sulfide with ketene each in the vapor phase at a temperature Within the limits of 150 to 350 F., and recovering thioacetic acid as a product of the process.

7. A process for the production of thioacetic acid comprising introducing hydrogen sulfide and ketene in a mole ratio of hydrogen sulfide to ketene within the limits of 2:1 to 5:1 to a reaction zone containing a solid adsorbent contact catalyst and therein reacting hydrogen sulde with ketene each in the vapor phase at a temperature Within the limits of 150 to 350 F. and recovering thioacetic acid as a productl of the process.

8. A process for the production of diacetyl sulide comprising introducing hydrogen suliide and ketene in a mole ratio of hydrogen sulfide to ketene Within the limits of 0.2:1 to 2:1 to a reac-l tion zone containing activated charcoal as a catalyst and therein reacting hydrogen sulde with ketene each in the vapor phase at a temperature within the limits of 150 to 350 F., and recovering diacetyl sulfide as a product of the process.

9. A process for the production oi diacetyl sulfide comprising introducing hydrogen suliide and ketene in a mole ratio of hydrogen sulde to ketene within the limits of 0.2:1 to 2:1 to a reaction Zone containing a solid adsorbent contact catalyst and therein reacting hydrogen suliide with ketene each in the vapor phase. at a temperature Within the limits of 150 to 350 F., and recovering diacetyl sulfide as a product of the process.

10. A process for the production of diacetyl sulfide, comprising reacting ketene with thioacetic acid in vapor phase in the presence of a solid adsorbent catalyst at a temperature within the range of 150-350 F., and recovering diacetyl suliide from the resulting reaction product.

l1. A process -for l the production of thioacetic 9 acid and diacetyl sulfide, comprising passing hydrogen sulfide and ketene each in the vapor phase and in a mol ratio of hydrogen sulfide to ketene within the limits of 0.2:1 to 8:1 into contact with a solid adsorbent contact catalyst selected from 5 the group consisting of an alumina, charcoal, and molybdenum sulfide, at a temperature within the limits 0f 50 to 400 F., whereby thioacetic acid and diacetyl sulde are formed by the vapor phase reaction of hydrogen sulde and ketene, 10

and recovering thioacetc acid and diacetyl sulde as products of the process.

12. The process of claim 11 wherein said catalyst comprises alumina.

13. The process of claim 12 wherein said cat- 15 alyst is molybdena-alumina.

WILLIE W. CROUCH.

10 References Cited in the le of this patent UNITED STATES PATENTS Name Date Ellingboe Dec. 3, 1946 Number OTHER REFERENCES Hurd et al., J. A. C. S., Vol. 54, Pp. 3427-3429 (1932).

Clarke and Hartman, J. A. C. S., vol. 46, pp. 1731-1733 (1924).

Hurd et a1., J. A. C. S., v01. 58, pp. 962-968 (1936).

Chick et al., Chem. Zentr., 1908, part II. Pp. 1018. 

11. A PROCESS FOR THE PRODUCTION OF THIOACETIC ACID AND DIACETYL SULFIDE, COMPRISING PASSING HYDROGEN SULFIDE KETENE EACH IN THE VAPOR PHASE AND IN A MOL RATIO OF HYDROGEN SULFIDE TO KETENE WITHIN THE LIMITS OF 0.2:1 TO 8:1 INTO CONTACT WITH A SOLID ADSORBENT CONTACT CATALYST SELECTED FROM THE GROUP CONSISTING OF AN ALUMINA, CHARCOAL, 